Best differential for road racing?
06-29-2006, 02:33 PM
#1
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Location: Sacramento, CA
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Best differential for road racing?
Hi guys, new user here. I have an 81 280zx that I did a turbo swap on for about the last 6 months. Right now I still have the stock 3.9 out back which kinda sucks for straight line/top end but i'm wondering if it might be good for the track? I have an 82zxt parts car that I can pull the 3.54 from. I've only heard that the higher gears for drag racing, but what about road courses? Thanks for any input. check my car out here
Brandon
Brandon
06-29-2006, 02:44 PM
#2
Big Poppa
Join Date: Jan 2005
Location: Mission, British Columbia
Posts: 4,499
it really depends on the track, nissan also made a 3.75 as well for these cars, your setup will depend on the track. now correct me if im wrong here guys, but ive also heard that the open diff is better for road racing around sharp corners, simply because the car needs less hp for the car to turn, if you had lsd, it would need mmore power, and more potential to spin, hence the need for the lsd in the drifting world. so if its a short tight track, use the 3.9, if its a long smooth course use the 3.54, or the 3.75.
06-29-2006, 03:13 PM
#3
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Join Date: Oct 2001
Location: Bay Area
Posts: 9,221
Yes, 'real' road racers have a number of different ratios that they use depending on the track they're competing at.
There's no 'one ratio fits all conditions'.
An advantage of the 3.545 gears in the turbo cars is to keep the car in the same gear and the boost on for longer periods of time. This is better for long sweeping tracks but can affect your exit speeds on tight corners.
As Shady mentioned, the LSD needs to be setup properly for the type of track as well. You get more initial understeer with an LSD going into a tight corner until the back end starts to come around and then you have more oversteer which people like to call a power slide which has now turned into drifting...
For my purposes, I prefer a 1.5 LSD with a 3.7:1 gears for general road racing my 240z and I have a 1.5 LSD with 3.545:1 gears for drag racing.
There's no 'one ratio fits all conditions'.
An advantage of the 3.545 gears in the turbo cars is to keep the car in the same gear and the boost on for longer periods of time. This is better for long sweeping tracks but can affect your exit speeds on tight corners.
As Shady mentioned, the LSD needs to be setup properly for the type of track as well. You get more initial understeer with an LSD going into a tight corner until the back end starts to come around and then you have more oversteer which people like to call a power slide which has now turned into drifting...
For my purposes, I prefer a 1.5 LSD with a 3.7:1 gears for general road racing my 240z and I have a 1.5 LSD with 3.545:1 gears for drag racing.
06-29-2006, 09:47 PM
#4
Originally Posted by lww
For my purposes, I prefer a 1.5 LSD with a 3.7:1 gears for general road racing my 240z and I have a 1.5 LSD with 3.545:1 gears for drag racing.
06-30-2006, 01:39 AM
#5
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Join Date: Mar 2004
Location: Brisbane, Australia
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Use a helical ATB LSD diff center like a Quaife if you can, they are better for road racing than the clutch type LSD's. This assumes the suspension basics are right eg no rear wheel lifting in corners.
06-30-2006, 09:17 AM
#6
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Originally Posted by NismoPick
Speaking of which... Do you know if the stock Z31T LSD was a 1 or 2 way?
06-30-2006, 09:21 AM
#7
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Originally Posted by 260DET
Use a helical ATB LSD diff center like a Quaife if you can, they are better for road racing than the clutch type LSD's. This assumes the suspension basics are right eg no rear wheel lifting in corners.
You can get a new Precision Gear - Power Brute clutch LSD center section for a little under $600 and have it installed and the pre-load set for your driving style and still be under the $1000 mark.
The Quaife will be nearly $1300 minimum and then you still have to have it installed by a knowledgeable diff guy easily driving the final price into the $1700 to $2000 range.
07-02-2006, 04:43 PM
#8
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Thanks for the input guys. I think i'm gonna still with the open 3.9 for a bit right now...get some track time and see what will work. Anybody here familiar with Infineon raceway? Thats where I plan to go in the next couple months.
Brandon
Brandon
07-03-2006, 09:42 AM
#10
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This is part of my problem... I want to move out of Cali, but I can't stand being somewhere that doesn't have SEVEN world class race tracks within driving distance...
From north to south: Thunderhill, Sears Point, Laguna Seca, Buttonwillow and Willow Springs in California with Reno-Fernley and Spring Mountain next door in Nevada!
All these tracks are on the ZDriver Frappr site at:
http://www.frappr.com/zdriver
From north to south: Thunderhill, Sears Point, Laguna Seca, Buttonwillow and Willow Springs in California with Reno-Fernley and Spring Mountain next door in Nevada!
All these tracks are on the ZDriver Frappr site at:
http://www.frappr.com/zdriver
07-03-2006, 01:10 PM
#11
Euro Z King
Join Date: Mar 2006
Location: Utrecht The Netherlands where owning a car is a CRIME!!
Posts: 387
Move to holland, we have the Dutch TT track ( world GP) the Zandvoort track ( F1 A1 DTM track), Spa Francochamp ( F1 and DTM and whatnot), Hockenheim (F1 DTM) Nurbergring Nordsleiffe ( does it need explenation???)
07-05-2006, 04:58 AM
#14
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Join Date: Mar 2006
Location: florida
Posts: 271
Problem with high rpms on the highway is that the car goes into open loop the minute the engine goes over 3500rpms.....or is it 3700.
Either way, you're just running on the map provided by the spring in the airflow meter and the temp sensors once over that speed.
Either way, you're just running on the map provided by the spring in the airflow meter and the temp sensors once over that speed.
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